1.4 and fabulous lens.....as is the 1.8..both very good glass and not expensive, relatively speaking.
Only hassle is with digital the old sensor needs cleaned more often.....
I use it on the FX now which gives its true 50mm but on my DX it works our around 70/75mm but a fabulous piece of gear.
Personally I think prime lenses are the best....if you can be bothered to carry a range with you.
Art